VulnerabilityPublished 3 Feb 2026Updated 4 Feb 2026

CVE-2025-67187: TOTOLINK A950RG router firmware · CVE-2025-67187 is a critical stack-based buffer overflow

Source CVE Database V5

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 09:15 UTC

CVSS 3.1 base score

9.8Critical

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

1. Immediately inventory and identify all TOTOLINK A950RG routers running the vulnerable firmware version V4.1.2cu.5204_B20210112 within the network. 2. Monitor vendor communications closely for official patches or firmware updates addressing this vulnerability and apply them as soon as they become available. 3. Until patches are released, restrict access to the affected devices by implementing network segmentation and firewall rules that limit inbound traffic to trusted management networks only. 4. Disable or restrict the setIpQosRules interface if possible, or any remote management features that expose this functionality. 5. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting exploitation attempts targeting this vulnerability. 6. Conduct regular network traffic analysis to identify anomalous behavior indicative of exploitation attempts. 7. Educate IT staff about the vulnerability and ensure incident response plans include procedures for compromised network devices. 8. Consider replacing vulnerable devices with alternative hardware if patching is delayed or unsupported. 9. Maintain up-to-date backups of router configurations to enable rapid recovery if compromise occurs.

Description

CVE-2025-67187 is a critical stack-based buffer overflow vulnerability in the TOTOLINK A950RG router firmware version V4.1.2cu.5204_B20210112. The flaw resides in the setIpQosRules interface within the /lib/cste_modules/firewall.so component, where the comment parameter lacks proper length validation. This vulnerability allows unauthenticated remote attackers to execute arbitrary code with high impact on confidentiality, integrity, and availability without user interaction. Although no known exploits are currently reported in the wild, the high CVSS score of 9.8 indicates a severe risk. European organizations using this router model could face significant disruption or compromise if targeted.

Impact

For European organizations, this vulnerability poses a significant threat due to the potential for complete compromise of affected routers. Exploitation could lead to unauthorized access to internal networks, interception of confidential communications, and disruption of network availability. Small and medium enterprises relying on TOTOLINK A950RG routers for internet connectivity or network segmentation may experience data breaches or operational downtime. Critical infrastructure sectors using these devices could face targeted attacks aiming to disrupt services or conduct espionage. The lack of authentication and user interaction requirements lowers the barrier for attackers, increasing the likelihood of exploitation. Additionally, compromised routers could be leveraged as entry points for lateral movement within corporate networks or as part of botnets for broader attacks. The overall impact includes loss of data confidentiality, integrity breaches, and denial of service conditions, all of which can have severe regulatory and financial consequences under European data protection laws.

CWE-121Stack-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #14
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Implementation
Implement and perform bounds checking on input.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/SunnyYANGyaya/cuicuishark-sheep-fishIOT/blob/main/ToTolink/A950RG/5024-setIpQosRules-comment-buffer.md (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 11 Feb 2026, 12:05 UTC

WeaknessesCWE-121

Technical details

References

Community reviews

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